Caroline Lucas called for a ‘progressive alliance’ in May 2015, after voters gave the Tories an outright majority.
Photograph: Clive Gee/PA

The morning after the EU referendum was not, for progressives, like the morning after any other defeat. It wasn’t just depressing, but disorienting. For Remainers used to thinking of themselves as the sensible mainstream the result was a rude shock. They hadn’t just lost, they were lost in a country they no longer recognised. People clearly weren’t thinking what they were thinking, after all.

And so, many will be drawn to the upbeat title of this book, with its can-do suggestion that actually there’s still a huge market for progressive parties if only they can get their act together.

The idea for a cross-party collection of essays stems from election night 2015, when the Green MP Caroline Lucas and her Liberal Democrat opponent Chris Bowers were chatting at their Brighton count about the futility of fighting each other when they actually agreed on so much.

A few months later they joined forces with the rising Labour star Lisa Nandy to produce this book, arguing not for a merger of their three parties, or even a formal electoral pact, but more cautiously for making common cause wherever possible. Why split the anti-Tory vote between them when, they suggest, the differences between many Labour, Lib Dem and Green candidates “are far smaller than the differences between figures who are at home in the Conservative party?”

That would be easier to swallow, perhaps, if Labour weren’t currently tearing itself in two over some of these supposedly small differences. Ironically, Nandy quit the front bench rather than work with Jeremy Corbyn in the very month this book was written.

But the prospect of a Labour split does, in a sense, add fresh urgency to the argument. Some Corbynites would clearly rather work with Greens, nationalists and fringe socialist parties than with the dreaded Blairites; some on the Labour right wonder if they now have more in common with centrists in other parties. Could there be an earthquake coming – a grand redrawing of the political map?

There are some highly readable essays here. Skim readers should skip straight to Duncan Brack’s practical account of lessons learned from Tony Blair and Paddy Ashdown’s efforts to forge a Lib-Lab pact in the 90s. The SNP MPs Mhairi Black and Chris Law shed interesting light on sticky relations with Labour at Westminster.

Yasmin Alibhai-Brown’s argument that the left has for the best of reasons failed to call out unacceptable beliefs and practices in ethnic minority communities is the best-written polemic in the book, whether you agree with it or not. True progressives, she argues, should operate without fear and favour – which means demanding that white liberals integrate better, too: “David Cameron talked about racial integration, but how many Asians get invited to his house?”

And while there’s no set progressive manifesto, some common themes do emerge: electoral reform to help smaller progressive parties, a basic universal income that might compensate for technology destroying low-skilled jobs, a shorter working week and a shift towards prioritising happiness over economic growth. An essay from the New Weather Institute’s David Boyle, arguing that the left should be proposing new ways of creating prosperity rather than just demonstrating that it “knows how to share it around”, meanwhile provides a necessary counterpoint to some more utopian contributions.

But the most important chapter here is probably the one many readers won’t like, in which the pollster John Curtice runs briskly through the electoral maths. As he writes, almost half the nation voted for broadly progressive parties in 2015 (49% backed Labour, the LibDems, Greens, SNP or Plaid Cymru, while 51% chose the Tories or Ukip). But it’s not as simple as concluding that first-past-the-post has cheated half the nation out of the liberal-left government it secretly wanted. Drill deeper and there’s worryingly little support for many of the assumptions made elsewhere in the book – for example, spending more on benefits even if it means higher taxes. Almost two-thirds of voters think ordinary people don’t enjoy a fair share of national wealth, yet only 40% favour redistribution from richer to poorer. Most think people should use their cars less for the sake of the planet – but when asked if they personally are willing to drive less, a majority aren’t. People like “what we might call the ‘sentiment’ of progressivism”, Curtice writes, but balk at what it means in practice. As for electoral reform to make every vote count, voters rejected that idea in a referendum just five years ago.

This barely addresses the gap between what voters are thinking and what progressives would like them to be thinking

And the yawning hole in this book is that it barely addresses this awkward gap between what voters are thinking and what progressives would like them to be thinking. Brexit may have come too late for the authors to reflect on, but progressive ideas took a pasting in May 2015 too, and the book doesn’t seem very interested in asking why.

The awkward reality hinted at in Curtice’s essay is that in Britain, progressives often struggle to get into government unless they hitch themselves to larger movements and identities. Labour has prospered by uniting progressive liberals, often middle class and urban, with a more socially conservative working-class movement. Tory modernisers thrived only by convincing traditional Conservatives to play along. The SNP blends progressive policies with identity politics. There are endless ways to make up the numbers, but growing big enough to govern usually involves compromises between those impatient for progress and those lagging behind; yet this book largely ignores the challenge posed by the latter.

Labour could add votes – although analysis suggests not enough to win a general election – by wooing Green voters, but the positions they’d strike to do so risk alienating others. Does anyone really imagine Labour voters who want to keep Trident, cut immigration, and who aren’t much interested in civil liberties have nowhere else to go? It’s not as simple as mentally shifting Green voters in marginal seats from one box to another, and assuming nothing else changes – and even if it were, scope for tactical voting is always limited by voters’ often deep attachments to their original tribes.

The authors are right to point out the madness of people who fundamentally agree on so much yet are scrapping over what looks like nothing. But if progressives aren’t careful, dreams of reuniting the left can become a place to hide from reality; a means of wishing away awkward truths about what voters think, and ducking the need to compromise with your own party. The trouble with collections of essays is that while each can be individually stimulating, they are often too contradictory to cohere into one clear story. What’s true of the literary project may prove true of the political one, too.

• The Alternative: Towards a New Progressive Politics is published by Biteback. To order a copy for £10.65 (RRP £12.99) go to bookshop.theguardian.com or call 0330 333 6846. Free UK p&p over £10, online orders only. Phone orders min p&p of £1.99.